When bats and mice interact with others of their kind, their brainwaves get in tune. It's not evidence of telepathy, but it does demonstrate how important connection is for social creatures. Similar synchronization was first observed between conversing humans 20 years ago, but the independent studies published today are the first proof the phenomenon occurs in non-human animals as well.
Research on human brain synchronization has been limited by the indirect nature of fMRI observations and the low-frequency focus of EEG machines. More interventionist methods are allowed on animals, whose brains are also simpler, potentially allowing us to learn much more about how brain alignment works.
"Because bats are extremely social and naturally live in highly complex social environments, they are a great model for tackling important scientific questions about social behavior and the neural mechanisms underlying it," said Dr Michael Yartsev of the University of California Berkeley in a statement.
Yartsev filmed male Egyptian fruitbats and tracked their brain activity while they mated, fought, and groomed. His wireless brain tracking devices are so precise, they can reveal the electrical activity of an individual neuron, as well as broader high-frequency brainwaves. These oscillations, particularly the more high-frequency waves, became correlated between bats at close quarters. Intriguingly, the correlations preceded social behavior to the point that Yartsev reports in Cell he could predict whether or not a bat would initiate an interaction based on how well its brainwaves matched a neighbor's.
Once the bats started to interact, the correlation got stronger, ruling out the possibility both bats' brains were showing the same response to the surrounding environment. It was not identical conditions but sharing a joint social experience that put bats on the same wavelength.
Coincidentally, graduate student Lyle Kingsbury has been conducting parallel research on pairs of male mice at UCLA. Kingsbury fitted the mice with tiny microendoscope calcium imagers weighing just 2 grams. In a separate Cell paper, he describes how when two mice are in a hierarchical interaction, the subordinate rodent's brain activity is set by that of the dominant one far more than the reverse. The greater the hierarchical difference, the more in tune the brains become. Just 8 percent of neurons in the brain regions studied set the process by responding to the actions of the other mouse.
In another statement, Yartseve explained his observations, saying: “When you and I are interacting, we are basically forming a closed loop.” Whether the loop is joined by our words or our body language, it leads to brains becoming linked.
People who struggle to pick up social cues may be less able to get on others' wavelength literally as well as figuratively. Kingsbury said the work could assist in understanding "how interbrain synchrony is disrupted in people with [autism and schizophrenia] and may provide novel information about possible interventions."
